From cd855011075d65a7e2f0c2ecf3cbaefa5fd57b15 Mon Sep 17 00:00:00 2001
From: Jonathan Cobb <jonathan@kyuss.org>
Date: Tue, 7 Jan 2020 17:30:48 -0500
Subject: [PATCH] add simple OneWayFlag constructor that returns false once

---
 .../java/org/cobbzilla/util/system/OneWayFlag.java   | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/main/java/org/cobbzilla/util/system/OneWayFlag.java b/src/main/java/org/cobbzilla/util/system/OneWayFlag.java
index 909791d..7f701bd 100644
--- a/src/main/java/org/cobbzilla/util/system/OneWayFlag.java
+++ b/src/main/java/org/cobbzilla/util/system/OneWayFlag.java
@@ -18,6 +18,11 @@ public class OneWayFlag extends AtomicBoolean {
     private final String name;
     private final Callable<Boolean> check;
 
+    public OneWayFlag(String name) {
+        this.name = name;
+        this.check = new ReturnFalseExactlyOnce();
+    }
+
     public OneWayFlag(String name, Callable<Boolean> check) {
         this.name = name;
         this.check = check;
@@ -42,4 +47,11 @@ public class OneWayFlag extends AtomicBoolean {
         return ok;
     }
 
+    private class ReturnFalseExactlyOnce implements Callable<Boolean> {
+        @Override public Boolean call() {
+            final boolean val = get();
+            if (!val) set(true);
+            return val;
+        }
+    }
 }